﻿//===================================================================================
// Microsoft patterns & practices
// Composite Application Guidance for Windows Presentation Foundation and Silverlight
//===================================================================================
// Copyright (c) Microsoft Corporation.  All rights reserved.
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE.
//===================================================================================
// The example companies, organizations, products, domain names,
// e-mail addresses, logos, people, places, and events depicted
// herein are fictitious.  No association with any real company,
// organization, product, domain name, email address, logo, person,
// places, or events is intended or should be inferred.
//===================================================================================
using System;
using System.Collections.Generic;
using System.Linq;

namespace Carcass.Events
{
  /// <summary>
  /// Implements <see cref="IEventAggregator"/>.
  /// </summary>
  public class EventAggregator : IEventAggregator
  {
    private readonly List<EventBase> _events = new List<EventBase>();

    /// <summary>
    /// Gets the single instance of the event managed by this EventAggregator. Multiple calls to this method with the same <typeparamref name="TEventType"/> returns the same event instance.
    /// </summary>
    /// <typeparam name="TEventType">The type of event to get. This must inherit from <see cref="EventBase"/>.</typeparam>
    /// <returns>A singleton instance of an event object of type <typeparamref name="TEventType"/>.</returns>
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1004:GenericMethodsShouldProvideTypeParameter")]
    public TEventType GetEvent<TEventType>() where TEventType : EventBase
    {
      TEventType eventInstance = _events.FirstOrDefault(evt => evt.GetType() == typeof(TEventType)) as TEventType;
      if (eventInstance == null)
      {
        eventInstance = Activator.CreateInstance<TEventType>();
        _events.Add(eventInstance);
      }
      return eventInstance;
    }
  }
}
